Thursday, 21 August 2014

It's not a vote for Yes, it's a vote for Salmond and the SNP - according to Salmond.

A common line of argument from Yes campaigners for Scottish Independence is:
"It's not a vote for Salmond or the SNP, it's a vote for Yes"
A Vote for Yes is a vote for theWhite Paper
Well I agree that's what it should be.  But oddly I don't often hear the same people saying (as they should)
"It's not a vote for Cameron or the Conservatives, it's a vote for No"
But that's an aside.  It turns out that Alex Salmond says that those Yes campaigners are just wrong. He said this in the Scottish Parliament.   Answering a question from Ruth Davidson, the Scottish Conservative leader, he said on 14th August: 
"I say to Ruth Davidson that, on September 18, if people in Scotland vote for what is in the white paper and the proposals to keep the pound, that is exactly what will happen and any Scottish politician who does not recognise the sovereign choice of the Scottish people will pay a heavy price. Incidentally, that is something that the Conservatives are long used to in political campaigns in Scotland."
I've put in the full quote to avoid being accused of quoting out of context. I don't care about the barb about the Tories, I care about this:
"on September 18, if people in Scotland vote for what is in the white paper and the proposals to keep the pound, that is exactly what will happen... the sovereign choice of the Scottish people"
Until I read that I really did believe that this was a vote for Yes, not for Salmond or the SNP or the white paper. But now the First Minister has told me - in the most sacred forum of Scottish democracy - that a Yes vote is a vote in toto for the white paper.  The white paper is exactly what will happen.

You can feel free to disagree with me.  But I'm quoting the First Minister.

If you vote Yes but don't agree with what Salmond, the SNP, and the Scottish Government have written in the white paper, then you are going against the "sovereign choice of the Scottish people". You don't want a lower corporation tax on the first day of independence?  No, you can't oppose that because it's against the sovereign choice of the Scottish people.

Maybe Alex Salmond misspoke.  Well, maybe all those other people he delights in quoting out of context in debates misspoke too.  Maybe he was joking.  Like Andy Burnham was.

But whether he meant to say what he said or not, it's essentially true.

There's an odd point of view that many Yes campaigners have, that somehow Scotland will be fundamentally more democratic as an independent country than the UK is.

Obviously, it will be more Scottish, but more democratic?

Let's assume that independence occurs on the timescale the Scottish Government wants, by March 2016.  There are no Scottish Parliamentary elections before then.  There is no suggestion of a second referendum on the outcome of negotiations, or a draft constitution.  There is no democratic control over the process except that exerted by The First Minister of Scotland (SNP), the Scottish Government (SNP), and the Scottish Parliament (absolute SNP majority).   Salmond has said (to his credit) that he would invite non-Yes campaigners into the negotiations, but the SNP will have absolute control of what happens.

Just like the rUK you say, with Cameron in control? Apart from anything else, rUK will enter negotiations with a two party government instead of one party, a two chamber legislature instead of one, and no referendum which they can say represents the "sovereign choice of the rUK people". And there is guaranteed to be a UK election before independence in which the negotiations are certain to be a central issue if Yes wins.

Scotland will be more democratic than rUK?   You can guess what I think.

To close, please remember what the First Minister implies:
"It's not a vote for Yes, it's a vote for Salmond and the SNP"
Or if you still insist I'm wrong (and I wish I was), remember that if you think 
"It's not a vote for Salmond or the SNP, it's a vote for Yes"
then at the very least you must also think:
"It's not a vote for Cameron or the Conservatives, it's a vote for No"

p.s. I'd like to thank Mulder1981 on Twitter for tweeting the picture below, which alerted me to the quote.  I spent a few minutes googling to confirm the quote was correct, since it seemed so unlikely. But it's true.

Wednesday, 13 August 2014

Why is Maths Hard?

Some slight thoughts about maths being hard.

Prompted by a couple of things I saw in quick succession.

First, this exchange on twitter about an interesting post about politeness. That post is interesting in its own right but not the point. The point is that Michiexile is a mathematician.

Second, this post about the lottery of what you happen to be interested in, where maths is definitely not in the author's bag.

This certainly strikes a chord with me. I happen to like maths and be good and it and it is seriously fascinating. But I have a couple of memories that are slightly discordant...

  • I once went at a job interview at HP Labs Bristol, where I did their logical thinking test and they said I'd got their third highest score ever (amongst many smart people.)   But I didn't find it impressive because I thought "You gave me the kind of test I am good at, so what?"   It didn't help that the same day they had some charlatan psychologist who administered a personality test and nearly gave me a nervous breakdown. 
  • A few years later I was talking with a good friend in a pub during my PhD, and he stopped and looked at me and said "You did Maths... at Cambridge... you must be very intelligent."  What was odd to me was that we had known each other for a couple of years, and surely his view of my intelligence shouldn't then have been judged by my CV.

The point I'm trying to make here is this.  Why should skill at Maths or Logic make you more intelligent that somebody skilled at something else.  Why do people think Maths is hard?

Is it because maths is the school subject with the highest ratio between compulsoriness (100% for a long time) and difficulty to some students (some reasonable percentage of people find it hard)?  So for example English language (in British schools) is similarly compulsory but not as obviously difficult.  Almost everyone can write essays even if they are not actually very good.  But in Maths, if you are really not very good at it, you can't do certain things at all.

I really don't know why people think Maths is hard but just asking the question.

Sunday, 10 August 2014

Why I Decided to vote No in the Independence Referendum

This post's title is very carefully worded: this is about why I decided to vote No.  This is not the same thing as why I am voting No. This is about the deciding moment: the straw that broke the camel's back, if you like.

We don't celebrate this enough!
Before I start, let me just say one thing that neither side has given the other enough credit for. We are having a referendum, and a 50.01% vote will decide it. The Yes side have not given the Noes, and David Cameron in particular, enough credit for the fact that they will accept the country being ripped apart by a wafer thin vote.  Compare situations like Quebec in Canada or Catalonia in Spain, where even a solid referendum majority might not be accepted.
From the Noes, there's not been enough credit to the Yes side for the fact there's been no hint of serious violence at any point, not just now but for decades.  Maybe the odd barfight or twitter trolling, but compare almost any other country's independence fight. This shows all of us what a great country we live in, both Scotland and the United Kingdom.

I always expected to vote No because I always felt I was a unionist. Much of it is emotional more than logical. I was brought up in England by a Scottish mother and English father. I have degrees from English and Scottish Universities. I have lived in Scotland for more than 20 years.  I have spent years of my life in Wales - split up over many family holidays throughout my life - and my sister and mother now live in Wales.  All of these have always felt to me to be part of the same country, they still do, and I want them to remain that way.

But while I always expected to vote No, I wasn't sure.  Maybe there would be the killer argument that convinced me to swap to Yes.  While this never came, neither did the killer argument to vote No.

What was it that decided me finally?

It was the currency union issue, which came to the front earlier in the year. But not in the way you might expect.

I don't think it matters very much whether there is currency union between between Scotland and the rest of the UK (from now on just "rUK", since it's important not to use England as shorthand for England and Wales and Northern Ireland.)   The other options are all credible and not obviously disastrous.  Scotland could use the pound without formal currency union, it could form its own currency (either linked to the pound or floating), or it could join the Euro.

Compare and contrast the standard Yes position on currency union and the debt.
  • It's Scotland's pound as much as rUK's!  We are leaving the UK. We get to keep control over the pound whatever rUK says!
  • It's the UK's debt!  We are leaving the UK. We get to throw away the debt if we feel like it!
The two issues are the same yet many Yes people treat them exactly opposite.  On the debt, all government debt was by definition taken out with the UK government.  Scotland would leave the UK and would therefore not be liable for it.  For that reason the UK government committed in January to honour 100% of the UK's debt whatever happened in the independence vote.   But this doesn't mean that Scotland gets to wave goodbye to its debt.  But the Yes campaign talks as if Scotland's share of UK debt is some kind of optional extra which Scotland can take or not as it wishes.

The situation is exactly the same with the currency as with the debt.  By voting to leave the UK the Scottish people would be voting to leave the pound.  Just as it is voting to leave the formal legal obligation to the debt, it is voting to leave the formal legal control of the pound.  But unlike the debt - which is treated as a "maybe aye and maybe hooch aye" deal - Scotland's choice is taken as absolute over control of the pound.  If it wants it, it gets it. Apparently, Scotland can decide if it has control over the rUK currency, but rUK is not allowed to decide if an external country controls its currency.

What is often said is that Scotland should receive it's fair share of the Bank of England's assets, and I completely agree.  The assets are things like its gold reserves, debt it is owed, and so on. (Not the key point, but interestingly there are several hundred billions of UK debt owed to the Bank of England because of quantitative easing, of which Scotland should get its share.)  So if the Bank of England's assets are (say) $500 billion, then an indy Scotland should get about $40 billion.

On the other hand, many people treat the pound as part of the assets of the Bank of England.  The pound as a currency is not an asset.  It's a medium of exchange in the UK.  It's not as if the UK is still on the gold standard and theoretically has reserves equal to all the money in the country.   In any case, it's indivisible.  And being indivisible, it would obviously devolve onto the rUK.  But it's not an indivisible asset, because it's not an asset.

If you still think the pound is an asset, here's what to do.  Put a value on it and ask in negotiations for about 8% of its value.  If you think the pound is an asset worth a trillion dollars, ask for $80 billion.  Obviously, as an asset, people can get different valuations but they'll be in the same ballpark. For example, the UK embassy in Washington might be worth $100 million or it might be worth $200 million, but some kind of estimate could be reached. If you're convinced the pound is an asset, value it. This is more or less a thought experiment: I can't imagine anyone being able to put a value on the pound, because it's not an asset.

The argument is pretty much the same as this: "We like having a permanent seat on the security council of the UN, and this seat is as much Scotland's as rUK's.  So after independence we'll have a permanent seat one month a year and rUK can have the seat the other 11 months."  Insisting as an absolute right to partial control of the pound after independence makes as much sense as asking for a permanent seat at the UN one month a year.

So my position is this, and is the same for both pound and debt.

  • If Scotland is independent, negotiations should include a fair solution to the question of what currency Scotland should use.  
  • If Scotland is independent, negotiations should include a fair share of existing UK assets and debts, on an agreed payment basis. 
And there is one final point
  • There is no direct linkage between debt and currency.  Both are important negotiating points, along with very many others. 
And it is precisely because of this last point that I decided to vote No.   After the currency question came into focus earlier in the year, with Osborne's intervention, it gradually became clear to me that pretty much all the SNP establishment believes it's reasonable to say that if they don't get their way with currency, they do not take on any debt.  

This is completely wrong.  It's immoral and - probably worse from the current point of view - it shows that the people involved have no idea how countries work when they are independent. Countries have debt and - except in extremis - they don't renege on their debt. 

It's completely reasonable - of course - for the Scottish negotiating position to start as wanting currency union.  It's also reasonable to expect some recompense if they don't get their way on currency union.  What kind of recompense would be reasonable?  For example, denominating debts in a new Scottish currency instead of pounds, or in dollars or in euros. Or agreeing that the debt would be on the interest rate the UK pays instead of the rate that Scotland would have to pay on the open market (higher since it would have no credit rating.)   There are probably lots of other options.

But that's not the way the Yes campaign thinks.  It takes as axiomatic that no currency union = no debt.  So an important but not critical point is equated with hundreds of billions of pounds of debt. Scottish politicians talk as if deciding to refuse currency union is the same thing as giving away debt.

What does getting currency union mean?  For all practical purposes it would mean Scotland getting to appoint one member of the Bank of England monetary policy committee.  That currently has 9 members, the Scottish Prime Minister would get to appoint a new one, with probably another one from rUK to make a total of 11 for an odd number to avoid ties.  There's been talk of the Bank of England becoming lender of last resort to rescue Scottish banks, which is a big deal, but if this happened it would probably mean massive contributions from the Scottish government.

And is currency union sustainable?  Ask the Czech Republic and Slovakia. They agreed currency union in the velvet divorce.  It lasted 6 weeks.

What does discarding its share of UK debt mean?

Well, the number Salmond uses is about £120 billion.  With roughly 5.3 million people in Scotland, this is close enough to £20,000 per person in Scotland.

The SNP position is - seriously - each Scottish person should get a present of £20,000 from the rUK government, if it doesn't get its way on currency union.

Except it's not £20,000, it's close to £40,000 per person.  Why?  Because the debt of about £120 billion as Scotland's share is net.  The UK's "whole of government accounts" say that "in 2012-13, the public sector liability was £2.9 trillion. Taking into account its assets of £1.3 trillion, the net liability was £1.6 trillion."   I assume that the £120 billion comes from £1.6 trillion times 0.08 = £128 billion, close enough.

Obviously Scotland wants (and should get) its fair share of current UK assets.  But the Yes campaign want the assets independent of debt, they want the assets and no debt if they don't get currency union. So actually the position is that it wants to forego about £230 billion of debt, while taking about £100 billion of assets.  So it wants a present of about £230 billion from rUK.  Roughly £40,000 per person in Scotland.

The Yes campaign wants to found Scotland as an independent nation on the idea that we take a present of £40,000 per person from citizens of rUK.  And this is on an imaginary equation between this outrageous pickpocketing, and a fairly minor negotiating point on the currency, which on nobody's imaginings can be worth £40,000 or even £20,000 per person.

I think I would like Alex Salmond if I met him.  I also think he's an incredibly able politician.  But he - and people who think like him on the debt-currency equation - are far too dangerous to be allowed anywhere near control of a major independent nation like Scotland.

It's often said by Yes campaigners who understand that not all potential Yes voters are SNP supporters, that this is not a campaign for one man or one party to lead Scotland.  This is true enough. But the currency/debt equation seems to be widespread, and not in one man's head.  And on the current plans of the Scottish Government, not only will all negotiations for independence be under their control, but there will not even be an election before independence.  That is, the first prime minister of Scotland and guider of negotiations and writer of provisional constitution would be Alex Salmond (or possibly his successor as SNP leader).

Alex Salmond is smart. From the very start of the serious independence debate, he has known that currency union won't happen. This is not because of statements made by Osborne or Balls or Alexander.  The UK has spent years not joining the Euro because of the potential loss of sovereignty. Can anyone imagine ceding even partial sovereignty over UK finances to Edinburgh moments after Scotland has left the Union?  It's totally irrelevant whether or not it's in the rUK's best interests or not. (Every country has the right to do things that are against its best interests.) For political reasons, even if not for economic, certainly rUK will not form a currency union with an independent Scotland.

And under Alex Salmond - or any credible successor - the intention is to found Scotland on taking £40,000 per person in Scotland from the people of the rest of the UK.

No thanks.

Tuesday, 10 June 2014

Why The Passing of the Turing Test is a Big Deal

June 10, 2014. 

A lot of my friends don't agree with me, but I think we should be celebrating the passing of the Turing Test.

Quick summary of the Turing Test?  Can people tell the difference between a computer printing responses on a screen and a person typing?  If not then .... well I think I'll leave what the consequences are.

Three days ago was the 60th anniversary of the death of Alan Turing.  The same day, there was a big announcement: The Turing Test had been passed.  Among others, for example, see this BBC News item.

Since this happened, and it got all over the media, there's been a bit of a backlash, with many in the "Artificial Intelligentsia" commenting negatively.  (I think the lovely name for the community I am a fully signed up member of  comes from John Searle.)  I think the main points in the backlash have been:

  • The narrow definition of the Turing Test that was passed is not important. Interrogators only had a 5 minute conversation and the chatbot only had to get a 30% pass rate (or fooling humans rate.)
  • The winning entry cheated, or more precisely gamed the rules, by pretending to be a thirteen year old Ukrainian boy, with limited English.  
  • The competition was organised by Kevin Warwick, who does not have a high level of respect in community, being viewed as a stunt-organiser. 
Taking the arguments in reverse order:

As an ad-hominem argument, the last point does not deserve response, except to express disappointment that it's even been brought up by people.  And of course to criticise it is also to criticise serious members of the AI community like Aaron Sloman and John Barnden, who took part.

There's no question the entry gamed the system.  In fact in my AI teaching at Strathclyde and St Andrews Universites for more than 15 years I've been talking about the wonderful paper "How To Pass The Turing Test By Cheating" by Jason Hutchens.  He won an earlier competition (without actually passing the Turing Test) and wrote a paper about how the tricks he used meant the Turing Test wasn't really worthwhile.  

The narrow definition of the Turing Test?  Well let's be fair here. This comes from Turing's original paper:
"I believe that in about fifty years' time it will be possible, to programme computers ... to make them play the imitation game so well that an average interrogator will not have more than 70 per cent chance of making the right identification after five minutes of questioning."
Let's take a moment to remark on Turing's remarkable prescience.  I think most people would agree that 60 years from his death (64 from the paper publication) is "about fifty years".   This man was absolutely amazing.  In fact, and I've said this before, I think Turing ranks as one of the three greatest British scientists, with Newton and Darwin.  What a guy.

So yeah, the Turing test that was passed comes from Turing's original paper. It's hard to criticise on that basis.

But no, the Turing test that was passed is definitely not important. But it's not important in the sense that it is not driving research in Artificial Intelligence. This is the sense that academics mean when they say whether something is important or not. In that sense, I agree it's not important.

But here's my point. The passing of the Turing Test is a big deal.

I mean this in a few senses.

The first one is this.  Computers are getting very good at fooling people. This is something it's good for people to know. I'd be surprised if the likes of John Barnden and Aaron Sloman were fooled, because they know what to look for in a chatbot. But people were fooled, and let's remember they knew they were participating in the Turing test. When you talk online to somebody, you might not be talking to a person even if they appear to be one.  If you're not a Ukrainian teenager, I'm not sure you should be talking to 13 year old Ukrainian boys on the internet, but still: if you think you are talking to a person, maybe you are not.

(Random aside: my surprise is that interrogators didn't wonder where the organisers had rustled up a Ukrainian teenager with good but not perfect English.)

Here is the sense in which I think the passing of the Turing Test is a very big deal indeed.

If people get the impression that Artificial Intelligence is here to stay and is playing a huge part in everyday life, they would be absolutely right.   And this is something that we in the Artificial Intelligentsia don't shout about enough.

It used to be said that Artificial Intelligence is the stuff we don't know how to get computers to do.  Because once we do know how to get them to do it, researchers in Artificial Intelligence move on to something else.   It's still true to an extent, but less so

Computer Chess?  You might remember a computer beating Garry Kasparov.  Since then computers have got much better.  Nowadays computers are dramatically better than the human world chess champion, but you don't hear about it because the champion doesn't want to get whupped by a computer so they never play.  A few years ago a mobile phone won a grandmaster level chess tournament.   That's Artificial Intelligence.  But - by the way - computers have massively improved the quality of human play, because talented teenagers can learn by playing against world class competition many times a day on their home computer.

Big data and data mining?  That's Machine Learning, probably the largest area of Artificial Intelligence.

IBM Watson beating champion quiz players in punning quizzes?  That's Artificial Intelligence.

Voice recognition, handwriting recognition?  That's Artificial Intelligence.

Computer chips do what they are meant to do?  That's Artificial Intelligence proving mathematically that they do.  When the Pentium chip first came out, there was a bug that cost Intel hundreds of millions of dollars (in mid 1990s dollars).  Now they avoid that cost through Artificial Intelligence.

Google translate?  Certainly not perfect but gives you an idea of what something written in another language is about?  That's Artificial Intelligence.

Robots who can walk? That's Artificial Intelligence.

Self driving cars on everyday roads?  That's Artificial Intelligence.  A few years ago that seemed like a ridiculous dream.  Now they're real.

Artificial Intelligence has pretty much done what it set out to do.  The above achievements are exactly the kind of things that the visionaries who founded Artificial Intelligence wanted to do.   All of the above achievements once looked like being close to science fiction: and I don't mean a long time ago, but in my memory. To give you an idea, today happens to be my 50th birthday.

 Like any other science there is much still to do.  And there are many grand challenges to overcome. The key challenge that we are nowhere close to achieving is what you might call general intelligence. All the examples above are incredibly specialised, and don't play nicely together. So I promise that the Artificial Intelligentsia is not worried yet about running out of interesting things to do with computers.

Artificial Intelligence has been just incredibly and remarkably successful.  The passing of the Turing Test three days ago is not a big deal on the scale of the achievements above.  But it does give us a chance to mark the very big deal that Artificial Intelligence has become.  If this stunt makes people more aware of this - to mark the anniversary of the tragically early death of a very great man - I think that is a good thing.

And finally, here is a punning sense in which the passing of the Turing Test is a big deal.  It's been passed, in a reasonable sense. We can stop talking about it.  The Turing Test has passed in another sense: it's over.  You can get computers to pass the Turing Test.  Big deal.

Wednesday, 4 June 2014

Yes For Independence, Because Eton

Last night I attended a debate about Scottish Independence at the University of St Andrews.  It was very good and well tempered on both sides.  

One of the arguments from the Yes side was that the UK Cabinet is dominated by Etonians. Obviously this is a major problem with Westminster politics, since one only needs to look at the education of the last few prime ministers.   I've examined the evidence and present it to you now, and you can see the point is completely definitive.  

  • Eton.  There you are.  David Cameron went to Eton. You see!  The point is proved. 

You might want to look away now, because is there any necessity to look back further?   You want to?  Ok.

  • Fettes College.  Well that is an Edinburgh school, but it has been called "Eton of the North". So maybe we can count it.  So yep, let's count it as showing the dominance of Eton, or at least posh public schools. 
Really, look away.  Stop reading.  The point is made!  
  • Rutlish Grammar School.  Perhaps not a surprise that John Major didn't go to a major public school.  Or even a public school.  But again, he's the Conservative exception to the rule.
  • Kesteven and Grantham Girls' School.  Maggie obviously couldn't go to Eton, as a woman. As the Conservative hate figure of recent times, she must have gone to a posh public school. Though oddly the school's history seems to suggest it was a grammar school.
Really, there is no need to carry on reading.  A couple of Tory Prime Ministers didn't go to Eton, and one of them was a woman so she couldn't.  
  • Eton.  There you are!  The point is confirmed.  Of course it's a bit embarrassing that this was a Scottish Prime Minister, Alec Douglas-Home, but perhaps we could pass a law banning First Ministers from having attended Eton.  
From now on backwards it's really easy to see the point, because it goes Eton (Macmillan), Eton (Eden), Harrow (Churchill), and Haileybury (Attlee).   More public schoolboys back to the Second World War.  So there you have it, from 1940 to 1964 and from 2010 to 2014, the UK has been governed by English public school pupils. 

Pay no attention to the period between 1964 and 2010, because it's irrelevant.  The fact that not a single Prime Minister of the United Kingdom in 46 years attended an English public school is totally irrelevant.

So if you don't like Eton, vote Yes for Independence. 

Author's note.  Like my previous piece, for avoidance of doubt I will state that this piece is not serious.  The point is to show that dominance of UK politics by Etonians, or even public school pupils, is not true. 

For avoidance of any more doubt, I don't think the educational makeup of the current cabinet is reason to vote against them.  The reason to vote against them is because you don't like their policies. I think that is a very good reason to vote against them: whether or not that is a good reason to vote for independence is another question. 

Tuesday, 20 May 2014

I Shall Vote Yes

I shall vote Yes because after three hundred years in the United Kingdom, Scotland is one of the richest countries in the world 
I shall vote Yes because I like the Queen
I shall vote Yes because I want to carry on using the British Pound 
I shall vote Yes because I don't want border posts between Scotland and England

I shall vote Yes because I want to keep watching the BBC
I shall vote Yes because I want to carry on charging non-Scottish British students for an education   
I shall vote Yes because I want Scotland to carry on spending 50% more on scientific research than it pays for 
I shall vote Yes because I hate Londoners greedily taking resources and not sharing them with Scotland
because I want Scotland to greedily take resources and not share them with Londoners  
I shall vote Yes because in 2010 I hated being ruled by a Westminster government that got as little as 35.6% of the vote in Scotland
I shall vote Yes because in 2010 I loved being ruled by a Holyrood government that got as much as 32.9% of the vote in Scotland   
I shall vote Yes because I want to be just like that country which is currently successful and not at all like that other country which I wanted to be like a few years ago  
I shall vote Yes because my definition of a bully is a unionist politician who doesn't do what I tell them to do 
I shall vote Yes because I want the Scottish Olympic team to have the same kind of success that the Scottish football team has 
I shall vote Yes because the word Yes is positive and the word No is negative    
I shall vote Yes because deep in my heart I believe that everything I like about the country I live in is Scottish and everything I don't like is British 

by Ian Gent
20 May 2014

Author's notes: 

This is based on "I shall vote Labour", a 1966 poem by Christopher Logue, though more directly on "I Shall Vote No" by A.R. Frith.

I am reliably assured that some people got through Frith's piece without realising it was not serious, so I will state a disclaimer.  My current expectation is actually that I will vote No.

Thursday, 19 December 2013

Ho, Ho, Who?

No, Virginia, I'm Not Santa
Interior, Parents' bedroom, Christmas Eve. 

Dad: Do you think you got away with it?

Mum: Yep.  She went straight to sleep.  Though when she was putting out the mince pie and the sherry, we got uncomfortably close to the bone... 

Interior, Child's bedroom, Christmas Eve, Fifteen Minutes earlier.

Virginia: Mum, it's him, isn't it?  I know Santa is Dr Who. 

M: Yes Virginia, of course Santa is Dr Who.

V: I worked it out!  It has to be.  How else could one person deliver presents to all the children in the world in one night?

M: They couldn't.

V: It's the TARDIS! He can go all over the world, street by street, and get into the TARDIS and go back in time a few minutes to go to the next street.  That way he doesn't have to travel at faster than light speeds or anything, he just goes back in time.  It's brilliant!

M: Well dear, don't spoil it for everyone.  They like to believe in magic.

V: Oh of course not, you should hear some of the silly things people at school believe!  But it's the TARDIS!   Obviously, how could Santa get all those presents for everyone into one sleigh? Ridiculous!  But the TARDIS, he just keeps filling it up and up and it never fills up, and off he goes with everyone's present.

M: What about a flat without a chimney like ours?  

V: Oh Mum, have you even watched Dr Who?  It's the sonic screwdriver!  That can open any lock in the world.  He just waves it and the door and walks in. And I know something else, too.

M: What's that, Virginia?

V: At school somebody told me Santa wasn't real because the Santa I met at the store looked different to the one at the town's Christmas lights switch-on.  But I know why... 

M: Ah, yes, umm ... 

V: He regenerated in between!  Obviously!  Of course he didn't look the same.  He'd probably been through ten regenerations and thousands of trips back in time going to different towns talking to children.

M: Time for bed dear. You wouldn't want to be awake when the Doct.. I mean when Santa comes. 

V: Night mum, I love you.  Don't worry, I won't tell anyone what I've figured out. 

Mum switches light out.  Switch back to scene in Parent's bedroom.  Wrapping last few presents.

Dad: She's a smart cookie. Just one little thing she didn't figure out.  Nobody ever talked about Santa and his police box.  Santa's TARDIS is still working and can look like a sleigh. 

M: His entire lifetime and all his regenerations as a Time Lord spent delivering presents on Earth.

D: And just for Christmas this year.  More than a thousand years to deliver to every house that celebrates Christmas.  At one minute a house.  And working 16 hours a day, no days off.  

M: Next year they sacrifice some other poor Time Lord to do it all again.  Why are they so cruel?

M&D: Here's to you, Time Lord.  We're thinking of you. 

Exterior, urban street decorated for Christmas.  TARDIS sound effect as sleigh materialises. Santa climbs out of sleigh and opens door with sonic screwdriver and walks in.  There is no spring in his step.